Are we getting smarter? If you mean “Do our brains have more potential at conception than those of our ancestors?” then we are not. If you mean “Are we developing mental abilities that allow us to better deal with the complexity of the modern world, including problems of economic development?” then we are. For most people, the latter is what counts, so I will let the affirmative answer stand. But scholars prefer to ask a different question, to which they attach a special meaning, namely “Are we getting more intelligent?” I will answer that question at the end of Chapter 2.

Whatever we are doing, we are making massive IQ gains from one generation to another. That in itself is of great significance. IQ trends over time open windows on the human condition that make us conscious of things of which we were only half aware. This book attempts to make sense of what time and place are doing to our minds. It has new things to say about cognitive trends in both the developed and the developing world and where they may go over the rest of this century. It falsifies a major hypothesis that suggests that IQ differences between the two worlds are set in the stone of genetic differences. It addresses the most recent debate about the death penalty, particularly attempts to obscure the relevance of IQ gains to who lives or dies. It shows that cognitive trends have rendered inaccurate the diagnosis of memory loss. Perhaps most disturbing, it adds a new dimension to the tendency of western adults and teenagers to grow apart since 1950.

However, all the topics covered do not fit neatly into the box of IQ trends over time. I have included new thinking and data on subjects of general interest: whether race and gender IQ differences are genetic or environmental in origin; how modernity (or lack of it) affects the cognitive abilities of women; whether old age has a darker side hitherto unperceived. And finally, I offer a diagnosis suggested by some 30 years in the field: that psychology has somehow drifted away from sociology and suffered thereby.

Five years ago I published What Is Intelligence? Beyond the Flynn Effect (2007) and updated it two years later in the expanded paperback edition (2009). I thought of updating it again. However, as indicated, my new thinking and discoveries did not advance the theory of intelligence so much as a whole range of issues concerning economic growth, the death penalty, aging, and group differences.

Nonetheless what was said in the previous book colors my approach and therefore, the next chapter summarizes its contents. I do not flatter myself that everyone who reads this will have read (or will want to read) my previous work. Still, even those who have read What Is Intelligence? may find the next chapter interesting. It gives, for the first time, a full account of adult gains on the WAIS (Wechsler Adult Intelligence Scale), and compares them to child gains on the WISC (Wechsler Intelligence Scale for Children). Moreover, when a book is condensed, connections emerge that were not so clear in the lengthy original.

As for the remainder of this book, Chapter 3 speculates about the distant past and cognitive trends over the rest of this century. It also traces trends on Raven’s Progressive Matrices in the UK over the last 65 years, and gives a final verdict on the role of nutrition. Chapter 4 criticizes those who make Daubert motions, so they can go on using uncorrected IQ scores to multiply death sentences. It also presents evidence that instruments in current use misdiagnose memory loss in both Britain and Sweden.

Chapter 5 looks at American vocabulary trends over the last half-century. It assesses whether adult gains are the result of the spread of tertiary education or the expansion of cognitively demanding work, and notes a worrying trend for the language used by parents and the language used by their children to diverge. It also analyzes whether high-IQ or low-IQ people are more at risk of a radical loss of cognitive ability in old age. The evidence suggests that while there is a bonus for being bright in retaining vocabulary, there is a levy on being bright in retaining analytic skills.

Chapter 6 argues that the differential performance of black and white Americans on Wechsler subtests does not indicate whether the black/white IQ gap is genetic or environmental in origin. It also shows that modern women match men on Raven’s Progressive Matrices, despite the fact that university women have a slightly lower IQ than university men.

Chapter 7 argues that something peculiar happens to the study of intelligence when it becomes sociologically blind. Chapter 8, the last chapter, offers a brief summary and ends with a tribute to g and Arthur Jensen.

James R. Flynn is the author of Does Your Family Make You Smarter? He is professor emeritus at the University of Otago, New Zealand, and a recipient of the University's Gold Medal for Distinguished Career Research. He is renowned for the 'Flynn effect', the documentation of massive IQ gains from one generation to another....